Trailing-blade coater including fluid seal



Sept. 20, 1966 F. GALER ETAL 3,273,536

TRAILING-BLADE COATER INCLUDING FLUID SEAL Filed June 26, 1961 5Sheets-Sheet 1 INVENTORS MERRILL F. GALER N MORRISON N.ST|LES QMLA/ZM4%,, Quid THEIR ATTORNEYS Sept. 20, 1966 M, F. GALER ETAL TRAILING-BLADEGOATER INCLUDING FLUID SEAL Filed June 26, 1961 5 Sheets-Sheet 2INVENTORS MERRILL F. GALER MORRISON N.STILE.S

THEiR ATTORNEYS p 20, 1966 M. F. GALER ETAL 3,273,536

TRAILING-BLADE COATER INCLUDING FLUID SEAL Filed June 26, 1961 5Sheets-Sheet 5 if Max angle 0 pressure I so -M|n.unge pressure 35-102Blade Sponge Rubber INVENTORS. MERRILL E GALER THEIR ATTORNEYS MORRISONN. STILES United States Patent 3,273,536 TRAILING-BLADE COATER INCLUDINGFLUID SEAL Merrill F. Galer, Monroe, and Morrison N. Stiles, Westport,Conn., assignors to Time Incorporated, New York, N.Y., a corporation ofNew York Filed June 26, 1961, Ser. No. 119,431 4 Claims. (Cl. 118-413)This is a continuation-in-part of the copending, but now abandonedapplication, Serial No. 720,587, filed March 11, 1958.

This invention relates to a spreading or coating apparatus embodying anovel blade-clamping and controlling apparatus in which the blade isresiliently clamped and acted on by an adjustable pressure-exertingmeans which not only makes it possible for the blade to align itselfwith the surface to be coated, but affords a control over the Weight orthickness of the coating applied by the blade not heretofore availablein conventional coating apparatus. The invention also relates to a novelblade-clamping apparatus in which provision is made for supplying asealing fluid to the end walls of the blade support so that a suitableseal can be obtained without impeding the freedom of movement of theblade.

In conventional coating apparatus, the coating blade is usually firmlyclamped against a blade support in position such that the coating edgeof the blade projects beyond the blade support. In this conventionaltype of coating apparatus, the only control over the weight or thicknessof the coating material applied to the surface to be coated (aside fromthe choice of Web, coating material and speed) is obtained bypositioning the blade support so as to regulate the pressure engagementbetween the blade and the surface to be coated. This conventionalcoating apparatus does not give adequate control over the blade, andmoreover, due to the rigid manner in which the blade is clamped causesthe irregularities in the blade such as defects in the edge, ripples, orlocalized strength discrepancies to show up as defects in the coatingThe problems encountered in the use of conventional blade-clampingapparatus in which the blade is rigidly clamped against a blade supportcan be illustrated by reference to FIGURE 1A of the drawings. Suchrigidly clamped blades are characterized by pressure flaws inherent inthe blade itself and in its support. For example, the uniformity ofpressure exerted by the blade edge E against the cylinder C isinfluenced by:

(1) the parallel relationship of the line A of the clamp I with theblade edge;

(2) the parallel relationship of the line B of the blade support P withthe blade edge;

(3) the evenness of strength in the entire bladefrom edge to back andside to side-(indicated by K); and

(4) the edge characteristics of the blade at or adjacent to the line E,particularly its freedom from ripples and minute cavities.

The blade-clamping apparatus of the present invention provides aresilient clamping means for a blade capable of limited movement on ablade support. The blade support carries an adjustable pressure-exertingmeans which acts against the blade and urges the coating edge thereofagainst the backup cylinder or the surface to be coated, thereby causingthe blade to come into the desired pressure engagement with the surfaceto be coated. In addition, the clamped edge of the blade is permittedthe necessary freedom of movement to permit the blade to arch slightly,the arched blade having the advantage of minimizing the effect of anyirregularities of the blade and the blade edge. By virtue of thisadjustment of the blade, the bladeclamping apparatus of the presentinvention provides not 3,273,536 Patented Sept. 20, 1966 only anexcellent means for controlling the weight or thickness of the film ofcoating material applied by the blade, but it accomplishes this resultin a way which makes it possible for the blade to align itself properlywith the surface to be coated and also in a way which minimizes theeffect of imperfections in the blade.

An ancillary feature of the present. invention is that it provides meansfor supplying a sealing fluid to the end walls of the blade support sothat a suitable seal can be obtained without impeding theabove-described adjustment of the blade. Since the preferred embodimentof the present invention the coating material is supplied to the surfaceto be coated across the upper surface of the blade and between end Wallsor dams, it is important that the end walls do not interfere with thenecessary movement and deflection which must be imparted to the blade.Accordingly, the present invention provides an elastic seal in the formof a fluid which is effective while at the same time affording thenecessary freedom of movement to the blade.

For a complete understanding of the present invention, reference can bemade to the detailed description which follows and to the accompanyingdrawings, in which:

FIGURE 1 is a perspective view of a coating apparatus constructed inaccordance with the invention;

FIGURE 1A is a diagrammatic illustration of a conventionalblade-clamping apparatus;

FIGURE 2 is a view taken along FIGURE 1;

FIGURE 3 is a view taken along FIGURE 2;

FIGURE 4 is an enlarged portion of FIGURE 3;

FIGURE 5 is a schematic view which illustrates the principle of thepresent invention;

FIGURE 6 is a cross-sectional elevation of an alternative embodiment ofthe invention in which the section is taken through an end wall of theapparatus;

FIGURE 6A is an enlarged fragmentary view of a portion of FIGURE 6; and

FIGURE 7 is a perspective view similar to FIGURE 2, but of thealternative embodiment shown in FIGURE 6.

Referring now to FIGURE 1 of the drawings, a blade support, indicatedgenerally by the numeral 10, is provided with end walls or dams 11 and12 spaced apart from each other and attached to the opposite ends of abase 13. Blocks 14 and 15 are mounted on the inner sides of the endwalls 11 and 12, respectively. The arcuately curved front edges 16 and17 of the end walls 11 and 12, respectively, are contoured incomplementary fashion to the closely spaced curved surface of thecylinder to confine the coating material between the end walls as it issupplied to a web in contact with the cylinder. However, a moreeffective seal is provided between the end walls and the cylinder byfelt pads 18 and 19 attached to arcuate edges of the blocks 14 and 15.

A coating blade 20 is carried by the blade support between the end Walls11 and 12, and the ends of the blade are accommodated between the base13 and the lower edges of the blocks 14 and 15. Thus, the upper surfaceof the blade and the inner surfaces of the end walls cooperate to form areservoir for the feed by pressure or by gravity of the coating materialto the coating edge of the blade and thence onto the web to be coated.

A blade clamp or pressure strip 25 is secured rigidly to the base 13 byscrews 26, and the clamp carries a resilient strip 27 (e.g., of foamrubber) inset in the forward bottom edge of the clamp which engages therear edge 21 of the blade. In addition, the base 13 carries a pluralityof spaced-apart pins 22, the lower ends 23 of which are threaded intothe base. These pins pass through corresponding but over-sized holes inthe rear edge of the blade, and the upstanding ends of the pins are rethe line 2-2 of the line 33 of 3 ceived in over-sized holes 24 of theclamp 25. The resilient clamp and the over-sized holes of the bladepermit limited freedom of movement to the blade when the tube 29 is notinflated.

When the blade support is mounted in its operative position in proximityto the web backup cylinder, the coating edge 28 of the blade 20 ispressed against the web by an inflatable neoprene tube 29 partiallyrecessed in the base 13 of the blade support. The coating edge of theblade overhangs the tube 29 slightly. The inflatable tube serves as anadjustable means of controlling the pressure of the blade against theweb and the backup cylinder. As illustrated in FIGURE 5 of the drawings,before air pressure is introduced into the inflatable tube, the blade issubstantially straight and in light pressure engagement with thecylinder. As the air pressure is increased in the inflatable tube, thecoating edge of the blade is held between the cylinder and the tube, andthe blade begins to deflect -or arch. Because of the resiliency of theoperative portion of the clamp and the limited freedom of movementafforded to the blade by the pins in the over-sized holes, tl1e clampededge of the blade is capable of accommodating itself to this deflectionor arching of the blade. In a typical example, an increase in the airpressure of the tube from 0 lb. to 30 lb. pressure will lift the coatingedge a of the blade approximately .050 in., the high point 17 of theblade about .132 in. and will change the angle x of the blade about 6,or in other words, change the angle which the blade makes with a linetangential to the cylinder from about 60 to about 54 as shown in FIGURE5.

Delicate control over the weight or thickness of the coating materialcan be exercised by regulating the pressure supplied to the inflatabletube. Moreover, as the blade arches as the result of the inflation ofthe tube, imperfections in the blade (ripple, for example) are correctedand the blade tends to self-align itself with the backup cylinder.Moreover, in operation the inflatable tube serves as a relatively softbackup cushion for the cylinder which improves the uniformity of thecoated film.

Another important feature of the coating apparatus of the presentinvention is the elastic seal provided at the front ends of the blade20. This seal is effective to form an enclosed reservoir which isdefined by the two end blocks 14 and 15 of the walls 11 and 12,respectively, of the blade and the web to be coated. Essentially, thisseal is provided by supplying a sealing fluid under pressure to thefront edges of the end walls, specifically to the space or slot 30between the upper surface of the blade and the lower edges of the blocks14 and 15, the pressure causing the fluid to flow toward the cylinder.The sealing fluid can be air, grease or other suitable fluid which willafford the blade the necessary freedom of movement.

In the embodiment shown in FIGURES 3 and 4 of the drawings, the sealingfluid is supplied through a passage 31 in communication with a sealingfluid supply under pressure to a arcuate recess 32 in the upper surfaceof the base 13 near the coating edge of the blade. The rear half of therecess 32 is filled by a plug 33 to insure that the sealing fluid willbe directed toward the coating edge of the blade. A hole 34 in the bladeabove the recess 32 affords the sealing fluid access to the slot 30.

It is apparent that the passage which supplies the sealing fluid to theslot or space 30 can be formed in the end walls 11 and 12, or the blocks14 and 15, in which case it will not be necessary to provide the holes34 in the blade.

By way of illustration, in the embodiment shown in FIGURES 6 and 7 ofthe drawings, each of the end walls 11 and 12 is provided with a passage36 therethrough which establishes communication between a source of thesealing fluid under pressure and the slot or space 30 between the bottomedge of the respective block 14 or 15,

as the case may be, and the upper surface of the blade.

The invention has been shown in preferred form and by way of exampleonly, and obviously, many variations and modification may be madetherein without departing from the spirit of the invention. Theinvention, therefore, is not to be limited to any specified form orembodiment, except insofar as such limitations are set forth in theclaims.

We claim:

1. A coating apparatus which cooperates with a rotatable cylinderserving as a back-up surface for a web to be coated comprising a coatingblade, a coating blade support holding the coating blade in position toengage the web, a pair of end walls carried by the blade supportadjacent the rotatable cylinder to confine the coating materialtherebetween, means defining a slot in the base of each end wall toreceive the side edge of the blade therein, the height of the slot beinggreater than the thickness of the blade, the coating blade protrudingforwardly of the end walls in the direction of movement of the cylinderand the web against the cylinder and defining a space forward of eachend wall between the blade and the surface to be coated, the forward endof each said slot communicating with one of said spaces, and passagemeans establishing communication between a source of fluid underpressure for supplying the fluid to said space to provide a fluid sealfor said space.

2. A coating apparatus as set forth in claim 1 including an inflatabletube accommodated by the blade support and acting against the bladealong the length of the blade to load the coating edge of the bladeagainst the web to be coated, the height of the said slots permittingthe coating blade to deflect as the loading pressure increases.

3. A coating apparatus as set forth in claim 1 including resilient meansalong the length of the blade and engaging the blade remote from thecoating edge, the resilient means permitting deflection of the coatingblade between the coating edge and the edge opposite the coating edge.

4. A coating apparatus as set forth in claim 1 includ ing a plurality ofpins mounted in the blade support and spaced along a surface of theblade support, and means defining oversized holes in the blade along theedge opposite the coating edge to receive the pins and afford the bladeslimited movement relative to the blade support.

References Cited by the Examiner UNITED STATES PATENTS 1,566,358 12/1925White 118 1,883,167 10/1932 Vickery 15256.51 1,912,605 6/1933 Vickery15--256.51 2,077,816 4/1937 Vickery I- 118 2,081,320 5/1937 Burgess 1882,176,418 10/1939 Daley 118-262 2,328,183 8/1943 Barrett 1184132,329,277 9/1943 Lodding 118 2,431,900 12/ 1947 Worthington 1012102,487,409 11/1949 Baker 15-256.51 2,579,181 12/1951 Faeber 1011512,732,773 1/ 1956 Smith 15256.51 2,890,473 6/1959 Scott 118-261 X2,914,788 12/1959 Smith et al 118 2,948,012 8/1960 Scott 15-256.513,026,942 3/ 1962 Faeber 118407 X 3,032,007 5/1962 McCaulitf 118259 X3,070,066 12/1962 Faeber 118413 MORRIS KAPLAN, Primary Examiner.

JOSEPH B. SPENCER, RICHARD D. NEVIUS,

Examiners.

J. A. HAUG, Assistant Examiner.

1. A COATING APPARATUS WHICH COOPERATES WITH A ROTATABLE CYLINDERSERVING AS A BACK-UP SURFACE FOR A WEB TO BE COATED COMPRISING A COATINGBLADE, A COATING BLADE SUPPORT HOLDING THE COATING BLADE IN POSITION TOENGAGE THE WEB, A PAIR OF END WALLS CARRIED BY THE BLADE SUPPORTADJACENT THE ROTATABLE CYLINDER TO CONFINE THE COATING MATERIALTHEREBETWEEN, MEANS DEFINING A SLOT IN THE BASE OF EACH END WALL TORECEIVE THE SIDE EDGE OF THE BLADE THEREIN, THE HEIGHT OF THE SLOT BEINGGREATER THAN THE THICKNESS OF THE BLADE, THE COATING BLADE PROTRUDINGFORWARDLY OF THE END WALLS IN THE DIRECTION OF MOVEMENT OF THE CYLINDERAND THE WEB AGAINST THE CYLINDER AND DEFINING A SPACE FORWARD OF EACHEND WALL BETWEEN THE BLADE AND THE SURFACE TO BE COATED, THE FORWARD ENDOF EACH SAID SLOT COMMUNICATING WITH ONE OF SAID SPACES, AND PASSAGEMEANS ESTABLISHING COMMUNICATION BETWEEN A SOURCE OF FLUID UNDERPRESSURE FOR SUPPLYING THE FLUID TO SAID SPACE TO PROVIDE A FLUID SEALFOR SAID SPACE.